INTRODUCTION This application note presents Power Factor Correction (P

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INTRODUCTION This application note presents Power Factor Correction (P

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AND8182/D Watt Universal Input Boost Using NCP1601A
INTRODUCTION This application note presents Power Factor Correction (PFC) boost regulator example circuit using NCP1601A Figure with design steps measurement. measurement shows that circuit greater than Power Factor under universal input Vac). NCP1601A latest Semiconductor low-power products which operate both Discontinuous Conduction Mode (DCM) Critical Mode (CRM). feature limits maximum switching frequency easier front-ended filter design feature limits current stress inductor, MOSFET diode better cost, size, reliability.
25:1
MUR460
1N4001
Input 1N5406
1N4001 MZP4745A
Output SPP07N60C3
NCP1601A
0.05
1000 0.15
Figure Application Schematic Example Circuit
Common low-power method usually presented Critical Mode (CRM) which with changing switching frequency. switching frequency become dramatically very high zero-crossing moment sinusoidal waveform. Sometimes, high switching frequency makes desirable problem. However, advantage over fixed-frequency
lower peak current which important that preferable high current stress moment. result, NCP1601 developed have both CRM. converter using NCP1601 intended operate most stressful moment zero-crossing moment. mode operation NCP1601 summarized Figure
Semiconductor Components Industries, LLC, 2004
December, 2004 Rev.
Publication Order Number: AND8182/D
AND8182/D
Current Inductor current,
Input current,
with voltage secondary winding with voltage This voltage goes capacitor When stage diode primary winding with voltage (Vout Vin) secondary winding with voltage (Vout Vin) This voltage goes capacitor result, biasing voltage will Vout which almost constant independent variation input voltage.
time Critical Mode
VCC(off)
Hence, auxiliary winding turn ratio selected 25:1 that 15.6
15.6
Figure Mode Operation NCP1601
DESIGN STEPS
Step Define Specifications Table Specifications
Input Output Switching frequency Vac, Around
capacitor experimentally found enough circuit startup transient tstart worst case input given that consumes typical UVLO margin 4.75 NCP1601A.
tstart 4.75 10-3
maximum overvoltage threshold limited which corresponds 443.75 when feedback resistor 1.95 (1.8 maximum offset feedback NCP1601. Hence, output capacitor used output circuit. Then, nominal output voltage
Vout 1.95
protection purpose, clamping Zener MZP4745A added prevent unwanted transient overvoltage damage. noted that circuit needs typical 11.4 capacitor reach starting threshold (13.75 typical) worst condition Vac.
tstart 13.75 11.4 10-3 Step Take Assumption Efficiency
Step Bias Supply Design
efficiency usually assumed 90%. Then, input power This input power will frequently used next design steps.
Step Calculate Current Stress
axial resistor used charge capacitor startup. worst case power dissipation this resistor 0.47 which smaller than
2652 Power 0.47
Vout
worst case input current rating happens when input Vac. input current 1.31 Aac. suffix denotes that value. This current stress mainly front-ended rectifier.
1.31
instantaneous maximum current stress stage will critical mode.
Figure Auxiliary Winding Bias Supply.
auxiliary winding bias supply Figure provide bias voltage after startup. needs higher than minimum operating voltage VCC(off) typical). When stage MOSFET primary winding
This current stress affects component selections current sense resistor, MOSFET, diode, inductor.
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Step Oscillator Capacitor Design
switching frequency either oscillator mode synchronization mode NCP1601. this application, oscillator mode. Figure NCP1601 data sheet shows that capacitor frequency kHz. Actually, this frequency only valid operation because with lower switching frequency. However, this frequency provides reference calculating inductor next design step.
9.35 Step Inductor Design
Vcontrol
2LIchPin CrampVac2
10-6 10-6 1.01 (680 10-12 2LIchPin CrampVac2
high line Vac,
Vcontrol
10-6 10-6 (680 10-12 2652
Step Check Switching Periods Ensure Sinusoidal Peaks
minimum inductance L(CRM) line obtained follows:
L(CRM) Vout
line Vac, switching period MOSFET time (t1) followed.
CrampVcontrol Vout 10-12 1.01 10-6
maximum value L(CRM) line. Hence, value greater than L(CRM) make circuit operate CRM. inductor therefore switching frequency CRM.
freq Vout 10-6
10.22 CrampVcontrol 10-12 1.01 7.07 10-6
high line Vac, switching period MOSFET time (t1) followed.
CrampVcontrol Vout
10-12 10-6
Step Ramp Capacitor Design
Maximum power obtained when Vcontrol Worst case line Vac.
Cramp 2LIch 10-6 10-6
17.92 CrampVcontrol
long switching period larger than switching period circuit operates maximum current stress minimized.
Step Current Sense Resistors Design
There typical background capacitance ramp NCP1601. Cramp selected small possible limit maximum power transfer. Marginally, external capacitor good enough this application.
Cramp
settings current sense resistor sense resistor defines zero current threshold IL(ZCD) overcurrent protection threshold IL(OCP) following design equations.
IL(OCP)
With this value Cramp, control voltage Vcontrol high line line condition obtained. line Vac,
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AND8182/D
IL(ZCD)
Because IL(ZCD) greater than zero, greater than 535.7 which gives IL(ZCD) When very close 535.7 (say IL(OCP) IL(ZCD) 26000 IL(ZCD) very small with finite IL(OCP). example, maximum stress then IL(ZCD)
IL(OCP) (200 10-6) 0.0032 0.028
hold-up time tHOLD which time power supply needs maintain voltage with specified range after dropout line voltage.
2Pout tHOLD Vout_min2 VOP_min2
IL(ZCD)
10-6) 0.0075 0.028
where Vout_min minimum value regulated output voltage full load Vop_min minimum input voltage driven load PFC. Because there particular specification hold-up time, this term further studied here. major output ripple component circuit usually rectified line frequency because cannot easily filtered inductors capacitors. operations mainly affect switching frequency ripple which always much smaller than rectified line frequency ripple hence generally neglected.
However, tolerance exists real world actual design only closed this one. When value 0.05 power dissipation
0.05 I2ac 1.312 0.05
Rout
order have IL(OCP) will
IL(OCP) 0.05 0.0032 (200 10-6)
Figure Low-Frequency Equivalent Circuit Output Stage
frequency output stage stage simplified into Figure line frequency current source rectified sinusoidal only frequency considered) value Iout(rms) simply Pout/Vout. Hence, peak-to-peak value Iout(pk-pk) follow:
Iout(pk Iout(rms) Pout 0.363 Vout
standard size resistor. then IL(OCP) IL(ZCD) also obtained.
IL(OCP) 1000 (200 10-6) 0.0032 3.936 0.05
that capacitor only energy storage media circuit Figure discharging time one-fourth line frequency shown Figure
discharging time ripple Vout
IL(ZCD)
1000 10-6) 0.0075 0.05
Step Output Capacitor Design
choice output capacitance usually dictated required hold-up time acceptable output ripple voltage given application. rule thumb, output capacitance generally mF/W. Hence, application needs output capacitance.
Figure Output Voltage Ripple
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AND8182/D
Hence, frequency output ripple obtained following:
0.354 17.7 10-6
percentage high frequency current (IL) getting into input side (Iin) follows.
(2pfCF) LFCF 2pfLF (2pfCF) 1000
sake safety, rating output capacitor always recommended nominal output voltage circuit other hand, NCP1601 circuit instantaneous output voltage affects instantaneous control voltage Vcontrol. output voltage ripple high, will make large ripple control voltage power factor dramatically reduced highly dynamic control voltage.
Step Input Filter Design
11.10 10-6
10-6
10-6
0.31%
and/or circuit needs input filtering circuit bypass high frequency current that input current consists frequency part only. simplest filtering circuit capacitor across input lines Figure input impedance assumed with input source value input impedance usually unavailable negligible most application. Hence, differential mode filtering inductor added calculation currents Figure This differential mode inductor usually exists form common mode inductors.
when other hand, addition filtering capacitor also draws frequency (i.e., line frequency current Figure increases overall magnitude input current same power frequency equivalent circuit Figure shown Figure equivalent resistance circuit equivalent resistance which modeled purely resistive property expressed follows.
Pout
Figure Filtering Capacitor Circuit
Figure Low-Frequency Equivalent Circuit Phasor Diagram
Therefore, percentage increase input current addition filtering capacitor obtained.
(2pfLCF) Vin2h2pfLCF Pout 10-6
Figure High-Frequency Equivalent Circuit Phasor Diagram
high frequency source Figure inductor current high frequency equivalent circuit Figure shown Figure Therefore, phasor diagram drawn
2652
101.95%
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Step Layout Design
Figures illustrate layout circuit. layout rules, control circuit located corner prevent unwanted high frequency noise from main power switching circuit. NCP1601A associated with bunch order capacitors which very sensitive. best handle them minimize trace distance. Hence, this bunch capacitors ideally located bottom layer NCP1601A.
trace connected impedance current sense resistor major source noise error. recommended minimize this trace distance. Finally, circuit layout single layer board. result, resistor added between MOSFET gate NCP1601A output. This circuit path provides large amount high current noise that nearby trace output feedback easily polluted. Hence, some surface mounted decoupling capacitors located there noise.
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AND8182/D
Figure Demo Circuit Layer Layout
Figure Demo Circuit Bottom Layer Layout
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AND8182/D
Step Fine Tuning Capacitor Vcontrol
unity power factor NCP1601 circuit greatly relies steady control voltage Vcontrol (pin large external capacitor this help reduce noise dynamics this voltage give decent power factor. However, capacitor large, will reduce dynamic response startup transient circuit.
MEASUREMENT
performance example circuit listed Table waveforms with different input voltages
Table Experimental Measurement Circuit.
Input 108.2 107.9 105.8 104.6 104.7 104.4 104.6 Output 370.5 100.8 384.8 101.2 385.2 99.8 391.2 99.8 394.2 100.1 394.8 100.3 400.9 100.5
also shown Figures Figures upper trace input current with A/div. center trace output voltage with V/div. lower trace boost input voltage with 100V/div. output voltage circuit (1.8 There roughly (96% 390) (100%) regulation window NCP1601. explains variation output voltage over wide input range Table improved front-ended capacitor reduced.
Efficiency 93.17% 93.83% 94.33% 95.41% 95.63% 96.05% 96.08%
0.995 8.3% 0.991 12.8% 0.990 11.3% 0.975 11.9% 0.952 16.7% 0.945 21.1% 0.901 38.9%
Figure Input Voltage
Figure Input Voltage
Figure Input Voltage
Figure Input Voltage
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AND8182/D
order illustrate capability both operation NCP1601, Figures taken. upper trace figures boost input voltage with V/div. lower trace voltage across 0.05 current sense resistor with mV/div that inductor current mode operation indirectly shown. Figure shows traces with time base that maximum minimum value boost input voltage observed this time base voltage across current sense resistor noisy study. Figure shows moment when boost input voltage maximum. illustrates that circuit operation this moment. Figure shows moment when boost input voltage minimum. illustrates that circuit operation.
Figure Current Sense Resistor Voltage
Figure Operation Near Peak
Figure Operation Zero Crossing
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AND8182/D
CONCLUSION
example circuit using NCP1601A presented. design steps measurement covered. noted that NCP1601 perform decent power factor
correction efficiency that suitable power applications. Major equations NCP1601 design listed appendix reference.
Appendix Bill Material NCP1601 Example Circuit
26-60-4030 009652038 NCP1601A 1N5406 1N4001 MUR460 MZP4745A PCV-2-105-02 CTX22-16885 SPP07N60C3 RE105 50MH71M4X7 UHD1E471MPD 450AXW100M18X40 VJ1206A101KXAA VJ1206Y154KXXA VJ1206A681KXAA VJ1206A102KXAA WSL2010-R0500-F Part Controller Standard Diode, Standard Diode,1 Fast Recovery Diode, Zener Diode, Inductor, 1000 Custom Transformer, 25:1:1 TO-220AB N-Channel MOSFET Noise Suppression Capacitor Aluminum Electrolytic Capacitor, Aluminum Electrolytic Capacitor, Aluminum Electrolytic Capacitor, 1206 Capacitor, 1206 Capacitor, 0.15 1206 Capacitor, 1206 Capacitor, 1000 Resistor, 0.05 Axial Resistor, Axial Resistor, Axial Resistor, Axial Resistor, Axial Resistor, Male Header Molex Description Manufacturer Semiconductor Semiconductor Semiconductor Semiconductor Semiconductor Coilcraft Cooper Coiltronics Infineon Okaya Rubycon Nichicon Rubycon Vishay Vishay Vishay Vishay Vishay Dale
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AND8182/D
Appendix Summary Equations NCP1601 Boost
Description Boost converter Critical Mode (CRM) Discontinuous Mode (DCM)
Vout
Vout
Vout
Vout
Input current averaged filter capacitor Voltage time Vton
Vout
Vout Vton
Vton Vcontrol LIpk CrampVcontrol
control Vout CrampVcontrol Vout
MOSFET on-time
constant unity Vcontrol constant unity
Switching period
constant unity Vcontrol constant unity
CrampVcontrol
Same
LIpk
CrampVcontrol Vout LIpk Vout
CrampVcontrol Vout Vout
Minimum Inductor Input impedance
L(CRM) Vout 2LIch CrampVcontrol
Same
Input power
Vac2CrampVcontrol 2LIch Pout hPin ramp control 2LIch Pin_max Vac2Cramp 2LIch
Same
Output power
Same
Maximum input power when Vcontrol
Same
Minimum ramp capacitor when Vcontrol Control voltage Vcontrol
Cramp Vctrl
2LIch Vac2
Same
2LIchPin CrampVac2
Same
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INTRODUCTION This application note presents Power Factor Correction (P

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